The present disclosure relates to semiconductor devices and methods of forming semiconductor devices. As semiconductor devices become more highly integrated, a capacitor having a sufficient capacitance in a limited area may be required. The capacitance of a capacitor is proportional to a surface area of an electrode and a dielectric constant of a dielectric film, and is inversely proportional to an equivalent oxide thickness of the dielectric film. Attempts to increase the capacitance of a capacitor in a limited area may include increasing a surface area of an electrode by forming a capacitor of a three dimensional structure, reducing an equivalent oxide thickness of a dielectric film, and using a dielectric film having a high dielectric constant.
Increasing a surface area of an electrode may increase a height of a lower electrode (or a storage electrode). Moreover, an effective surface area of a lower electrode using a hemi-spherical grain (HSG) may be enlarged, and an inside area and an outside area of a cylinder using a one cylinder storage (OCS) electrode may be used. A dielectric film having a high dielectric constant may be a metal oxide film such as titanium dioxide (TiO2) and tantalum pentoxide (Ta2O5) or a ferroelectric film of perovskite structure (e.g., lead zirconate titanate (PZT) (PbZrTiO3) or barium strontium titanate (BST) (BaSrTiO3)).